// addrspace.cc 
//	Routines to manage address spaces (executing user programs).
//
//	In order to run a user program, you must:
//
//	1. link with the -N -T 0 option 
//	2. run coff2noff to convert the object file to Nachos format
//		(Nachos object code format is essentially just a simpler
//		version of the UNIX executable object code format)
//	3. load the NOFF file into the Nachos file system
//		(if you haven't implemented the file system yet, you
//		don't need to do this last step)
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "system.h"
#include "addrspace.h"
#include "noff.h"
#include "table.h"
#include "synch.h"

extern "C" { int bzero(char *, int); };

Table::Table(int s) : map(s), table(0), lock(0), size(s) {
    table = new void *[size];
    lock = new Lock("TableLock");
}

Table::~Table() {
    if (table) {
	delete table;
	table = 0;
    }
    if (lock) {
	delete lock;
	lock = 0;
    }
}

void *Table::Get(int i) {
    // Return the element associated with the given if, or 0 if
    // there is none.

    return (i >=0 && i < size && map.Test(i)) ? table[i] : 0;
}

int Table::Put(void *f) {
    // Put the element in the table and return the slot it used.  Use a
    // lock so 2 files don't get the same space.
    int i;	// to find the next slot

    lock->Acquire();
    i = map.Find();
    lock->Release();
    if ( i != -1)
	table[i] = f;
    return i;
}

void *Table::Remove(int i) {
    // Remove the element associated with identifier i from the table,
    // and return it.

    void *f =0;

    if ( i >= 0 && i < size ) {
	lock->Acquire();
	if ( map.Test(i) ) {
	    map.Clear(i);
	    f = table[i];
	    table[i] = 0;
	}
	lock->Release();
    }
    return f;
}

//----------------------------------------------------------------------
// SwapHeader
// 	Do little endian to big endian conversion on the bytes in the 
//	object file header, in case the file was generated on a little
//	endian machine, and we're now running on a big endian machine.
//----------------------------------------------------------------------

static void 
SwapHeader (NoffHeader *noffH)
{
	noffH->noffMagic = WordToHost(noffH->noffMagic);
	noffH->code.size = WordToHost(noffH->code.size);
	noffH->code.virtualAddr = WordToHost(noffH->code.virtualAddr);
	noffH->code.inFileAddr = WordToHost(noffH->code.inFileAddr);
	noffH->initData.size = WordToHost(noffH->initData.size);
	noffH->initData.virtualAddr = WordToHost(noffH->initData.virtualAddr);
	noffH->initData.inFileAddr = WordToHost(noffH->initData.inFileAddr);
	noffH->uninitData.size = WordToHost(noffH->uninitData.size);
	noffH->uninitData.virtualAddr = WordToHost(noffH->uninitData.virtualAddr);
	noffH->uninitData.inFileAddr = WordToHost(noffH->uninitData.inFileAddr);
}

int bzero_Page(char* a, int startPage)
{
	int startPos = startPage*PageSize;
	if(startPage < 0){
		printf("Invalid physical page during process creation.\n");
		return -1; //some error
	}
	for(int i = 0; i < PageSize;i++)
	{
		a[startPos+i] = 0;
	}
	return 0; //successful
}
//----------------------------------------------------------------------
// AddrSpace::AddrSpace
// 	Create an address space to run a user program.
//	Load the program from a file "executable", and set everything
//	up so that we can start executing user instructions.
//
//	Assumes that the object code file is in NOFF format.
//
//	"executable" is the file containing the object code to load into memory
//
//      It's possible to fail to fully construct the address space for
//      several reasons, including being unable to allocate memory,
//      and being unable to read key parts of the executable.
//      Incompletely consretucted address spaces have the member
//      constructed set to false.
//----------------------------------------------------------------------
extern Lock *PhysMapLock;
extern BitMap* PhysMap;
AddrSpace::AddrSpace(OpenFile *executable, int spaceId) : fileTable(MaxOpenFiles) {
    NoffHeader noffH;
    unsigned int i, size;
	int physid, physaddr, offset;	//physid is to find a physical page to allocate
									//physaddr is the physical address of main memory to copy code and initialized data
    // Don't allocate the input or output to disk files
	unsigned int bound;  //The bound to decide whether a page is in the executable or not 
	unsigned int readOnlyPagesNum;
	pageTableLock = new Lock("pageTableLock");
	 
    fileTable.Put(0);
    fileTable.Put(0);
	
	currentExecutable = executable;
	
    executable->ReadAt((char *)&noffH, sizeof(noffH), 0);   //Read the file header from the executable file
    if ((noffH.noffMagic != NOFFMAGIC) && 
		(WordToHost(noffH.noffMagic) == NOFFMAGIC))
    	SwapHeader(&noffH);
    ASSERT(noffH.noffMagic == NOFFMAGIC);

    size = noffH.code.size + noffH.initData.size + noffH.uninitData.size;
    numPages = divRoundUp(size, PageSize) + divRoundUp(UserStackSize,PageSize);   // #define divRoundUp(n,s)    (((n) / (s)) + ((((n) % (s)) > 0) ? 1 : 0))
                                                // we need to increase the size
						// to leave room for the stack
	
	maxnumPages = divRoundUp(size, PageSize) + divRoundUp(UserStackSize,PageSize)*MAXFORKNUM;
	//printf("DEBUG: The maxnumPages is %d",maxnumPages);
    size = numPages * PageSize;
	
	readOnlyPagesNum = divRoundDown(noffH.code.size, PageSize);
	bound = divRoundUp(noffH.code.size+noffH.initData.size, PageSize);
	
//    ASSERT(maxnumPages <= NumPhysPages);		// check we're not trying
						// to run anything too big --
						// at least until we have
						// virtual memory

    DEBUG('a', "Initializing address space, num pages %d, size %d\n", numPages, size);
	DEBUG('a', "							max number of pages %d", maxnumPages);
// first, set up the translation 
    pageTable = new newPageTableEntry[maxnumPages];
	//added by Tang
	//	assume that initialized data is just followed code in executable
	//PhysMapLock->Acquire();
	//offset = 0;
	
	
	for(i = 0; i < numPages; i++){
		
		/*physid = PhysMap->Find();
		if(physid == -1){
			printf("Physical address is full!");
			return;
		}
		physaddr = physid*PageSize;*/
		pageTable[i].virtualPage = i;
		pageTable[i].physicalPage = -1;  //Does not really matters
		pageTable[i].valid = false;
		pageTable[i].use = false;
		pageTable[i].dirty = false;
		pageTable[i].processId = spaceId;
		//pageTable[i].space = this;
		
		if(i<readOnlyPagesNum){
			pageTable[i].readOnly = true;
			
		}
		
		else{
			pageTable[i].readOnly = false;
		}
		
		if(i<bound) {
			pageTable[i].diskLocation = EXECUTABLE;
			pageTable[i].byteOffset = noffH.code.inFileAddr+i*PageSize;
			//printf("tangDEBUG: AddrSpace: The location of vpn %d is %d; thread ID is %d, process Id%d\n",i,EXECUTABLE,0,spaceId);

		}
		else {
			pageTable[i].diskLocation = NOTONDISK;
			pageTable[i].byteOffset = -1;
			//printf("myDEBUG: AddrSpace: The location of vpn %d is %d; thread ID is %d, spaceId %d\n",i,NOTONDISK,0,spaceId);
		}
		
/*		
		iptLock->Acquire();
		//modify ipt
		ipt[physid].virtualPage = i;
		ipt[physid].physicalPage = physid;
		ipt[physid].valid = true;
		ipt[physid].use = false;
		ipt[physid].dirty = false;
		ipt[physid].processId = spaceId;
		//ipt[physid].space = this;

		if(i<readOnlyPagesNum){
			pageTable[i].readOnly = true;
			ipt[physid].readOnly = true;
		}
		else{
			pageTable[i].readOnly = false;
			ipt[physid].readOnly = false;
		}

		//printf("\nAllocating physical page %x to virtual page %x to process with id %d", physid, i, spaceId);
		iptLock->Release();
		
		bzero_Page(machine->mainMemory, pageTable[i].physicalPage);
		if(i*PageSize < noffH.code.size+noffH.initData.size){

//		    DEBUG('a', "Initializing code/data segment, at 0x%x, size %d\n", physaddr, PageSize);
			executable->ReadAt(&(machine->mainMemory[physaddr]), PageSize, noffH.code.inFileAddr+i*PageSize);
//			offset += PageSize;
		}
		
	*/
	}
	
	for(;i<maxnumPages;i++){
		pageTable[i].virtualPage = i;
		pageTable[i].physicalPage = -1;
		pageTable[i].valid = false;
		pageTable[i].use = false;
		pageTable[i].dirty = false;
		pageTable[i].processId = spaceId;
	}
	//PhysMapLock->Release();
	
	
}

//----------------------------------------------------------------------
// AddrSpace::~AddrSpace
//
// 	Dealloate an address space.  release pages, page tables, files
// 	and file tables
//----------------------------------------------------------------------

AddrSpace::~AddrSpace()
{
    delete pageTable;
}

//----------------------------------------------------------------------
// AddrSpace::InitRegisters
// 	Set the initial values for the user-level register set.
//
// 	We write these directly into the "machine" registers, so
//	that we can immediately jump to user code.  Note that these
//	will be saved/restored into the currentThread->userRegisters
//	when this thread is context switched out.
//----------------------------------------------------------------------

void
AddrSpace::InitRegisters()
{
    int i;

    for (i = 0; i < NumTotalRegs; i++)
	machine->WriteRegister(i, 0);

    // Initial program counter -- must be location of "Start"
    machine->WriteRegister(PCReg, 0);	

    // Need to also tell MIPS where next instruction is, because
    // of branch delay possibility
    machine->WriteRegister(NextPCReg, 4);

   // Set the stack register to the end of the address space, where we
   // allocated the stack; but subtract off a bit, to make sure we don't
   // accidentally reference off the end!
    machine->WriteRegister(StackReg, numPages * PageSize - 16);
    DEBUG('a', "Initializing stack register to %x\n", numPages * PageSize - 16);
}

//----------------------------------------------------------------------
// AddrSpace::SaveState
// 	On a context switch, save any machine state, specific
//	to this address space, that needs saving.
//
//	For now, nothing!
//----------------------------------------------------------------------

void AddrSpace::SaveState() 
{}

//----------------------------------------------------------------------
// AddrSpace::RestoreState
// 	On a context switch, restore the machine state so that
//	this address space can run.
//
//      For now, tell the machine where to find the page table.
//----------------------------------------------------------------------

void AddrSpace::RestoreState() 
{	int i;
    //machine->pageTable = pageTable;
    //smachine->pageTableSize = maxnumPages;
	//iptLock->Acquire();

	for(i=0;i<TLBSize;i++){
	//check current tlb entry valid and dirty bit
	//if valid and dirty, propagate dirty bit to ipt
		if((machine->tlb[i].valid == true) && (machine->tlb[i].dirty == true) && (ipt[machine->tlb[tlbCounter].physicalPage].use == false)){
			ipt[machine->tlb[i].physicalPage].dirty = true;

		}
	//invalidate tlb entry
	machine->tlb[i].valid = false;
	}

	//iptLock->Release();
}